The objectives are: 1) to establish the validity of IADsp (integral of the vector spatial magnitude during initial abnormal depolarization) to estimate infarct volume; 2) to evaluate the role of infarct size estimated from IADsp to predict clinical outcome (shock, congestive failure, survival rate); 3) to describe the evolution of IADsp; 4) to compare the predictiveness of IADsp to Selvester's point system using QRS criteria, recorded by the standard 12 lead ECG, to estimate infarct volume; 5) to evaluate the sensitivity and specificity of dm/dt (rate of change of the vector spatial magnitude) in diagnosis of myocardial infarction; 6) to describe dm/dt in patients without infarcts; 7) to establish the validity of secondary vectorcardiographic predictors of infarct size: the integral of the vector spatial magnitude during late depolarization (LADsp) for patients with inferior infarcts, and the integral of the voltage recorded the X lead (Area X) for patients with anterior infarcts. The study group will consist of patients with acute myocardial infarction, determined either postmortem or by angiography and ventriculography (if they do not expire); the control group will consist of people without a history of heart disease. Vectorcardiograph analysis will be done by computer. Pathological analysis will include incubation in nitro blue tetrazolium, volume measurement by displacement, histochemistry, and planimetry. Statistical tests will include survival analysis, Chi Square, and linear regression analysis.